For more than 25 years waterproofing substrates, in the form of flexible sheet materials, have been manufactured for waterproofing areas of potential water flow, such as over concrete decks, plaza decks, concrete foundations, and the like. One such waterproofing sheet material manufactured by W. R. Grace & Co., is called BITUTHENE.RTM. formed from a water-impermeable membrane, such as polyethylene, polypropylene or polyvinyl chloride, and a layer of a bituminous composition containing asphalt, tar or pitch and natural or synthetic rubber, having a ratio by weight of bitumin to rubber greater than about 80:20, and up to about 95:5, as described in U.S. Pat. Nos. 3,900,102 and 3,741,856 of John Hurst. As disclosed in the Hurst patents, because of the adhesive nature of the bituminous adhesive layer, a protective coating is needed, such as siliconized release paper, that is removably adhered to the bituminous adhesive composition layer to prevent the adhesive layer from adhering to itself during manufacture, handling and installation, or upon manufacture of the waterproofing material in roll form. In order to install the waterproofing article at an area of potential water flow, it is necessary to remove the release paper, in very large and cumbersome sheets, from the adhesive layer for contact of the adhesive layer against the area of potential water flow, e.g., against a concrete surface.
Similar release papers are applied to this Assignee's waterproofing membrane structures, as disclosed in this Assignee's Harriett U.S. Pat. Nos. 4,656,062; 4,810,573; 4,733,989; 4,787,780; 4,668,724; and 4,534,926; all hereby incorporated by reference. A sheet of release paper is applied over the bentonite clay/elastomer or polypropene or polybutene compositions described in this Assignee's aforementioned patents to prevent the waterproofing materials from adhering to themselves during manufacture, handling and installation, or when the materials are manufactured in roll form.
In accordance with the present invention, it has been found that a coating of a water-soluble polymer, preferably polyvinyl alcohol, having a desired degree of water-solubility, eliminates the disadvantages of the necessity of applying a stripable release paper onto the adhesive side of the waterproofing article. Further, quite surprisingly, the water-soluble polymer acts like an anaerobic sealant to tenaciously bond the waterproofing article to the surface of the substrate upon at least partial hydration of the water-soluble polymer layer, with or without an adjacent layer of an adhesive material.
While water-soluble polymers have been used over water-permeable facing sheets for preventing premature hydration of a water-swellable clay layer thereunder, as disclosed in this Assignee's Alexander U.S. Pat. Nos. 5,053,265; 5,063,100 and 5,180,255, the water-soluble polymers have not been recognized as adhesive materials, and have not been used to coat an underlying adhesive layer.